M E 345
Professor John M. Cimbala
Lecture 38
Today, we will:
•
Review the pdf module: Linear Velocity Measurement and do some example problems
Example: Velocity measurement
Given: Doppler radar is used to measure the speed of a
baseball as sketched (not to scale). The radar frequency is
12,000 MHz.
Pitcher’s
mound
To do: Calculate the maximum angle θ that will yield less
than 1% error in measuring the speed of the baseball.
Solution:
V
θ
Doppler
radar
Example: Velocity measurement
Given:
The LDV system in the M E 325 fluids lab uses a red helium-neon laser with
wavelength λ = 632.8 nm. The angle between the two beams is α = 13.53o. The system is
used in a small water tunnel with a speed range of -1 to 1 m/s.
To do:
Solution:
Calculate the maximum expected frequency (in units of kHz) of the LDV output.